tests/test-push-checkheads-pruned-B5.t

convert: don't drop commits that are empty in the source when using --filemap

I ran into this when using `hg lfconvert --to-normal` (which uses the filemap
class internally), and saw that commits with nothing but a branch change were
dropped.  We could put in an option that only lfconvert uses internally.  But
silently dropping anything other than a commit where all changes were excluded
seems unintended.  For example, there's a message in mercurial_sink.putcommit()
if it drops an empty commit.  (And the reason that isn't kicking in here is
because lfconvert isn't passing --filemap, so the self.filemapmode conditional
there is always False.)

The naive change of `return not files` broke test-convert-filemap.t, so this is
a little more elaborate than needed for converting from largefiles.

====================================
Testing head checking code: Case B-5
====================================

Mercurial checks for the introduction of new heads on push. Evolution comes
into play to detect if existing branches on the server are being replaced by
some of the new one we push.

This case is part of a series of tests checking this behavior.

Category B: simple case involving pruned changesets
TestCase 5: multi-changeset branch, mix of pruned and superceeded

.. old-state:
..
.. * 3 changeset branch
..
.. new-state:
..
.. * old head is pruned
.. * old mid is superceeded
.. * old root is pruned
..
.. expected-result:
..
.. * push allowed
..
.. graph-summary:
..
..   B ⊗
..     |
..   A ø⇠◔ A'
..     | |
..   B ⊗ |
..     |/
..     ●

  $ . $TESTDIR/testlib/push-checkheads-util.sh

Test setup
----------

  $ mkdir B5
  $ cd B5
  $ setuprepos
  creating basic server and client repo
  updating to branch default
  2 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ cd server
  $ mkcommit B0
  $ mkcommit C0
  $ cd ../client
  $ hg pull
  pulling from $TESTTMP/B5/server
  searching for changes
  adding changesets
  adding manifests
  adding file changes
  added 2 changesets with 2 changes to 2 files
  new changesets d73caddc5533:821fb21d0dd2 (2 drafts)
  (run 'hg update' to get a working copy)
  $ hg up 0
  0 files updated, 0 files merged, 1 files removed, 0 files unresolved
  $ mkcommit B1
  created new head
  $ hg debugobsolete --record-parents `getid "desc(A0)"`
  obsoleted 1 changesets
  2 new orphan changesets
  $ hg debugobsolete `getid "desc(B0)"` `getid "desc(B1)"`
  obsoleted 1 changesets
  $ hg debugobsolete --record-parents `getid "desc(C0)"`
  obsoleted 1 changesets
  $ hg log -G --hidden
  @  25c56d33e4c4 (draft): B1
  |
  | x  821fb21d0dd2 (draft): C0
  | |
  | x  d73caddc5533 (draft): B0
  | |
  | x  8aaa48160adc (draft): A0
  |/
  o  1e4be0697311 (public): root
  

Actual testing
--------------

  $ hg push
  pushing to $TESTTMP/B5/server
  searching for changes
  adding changesets
  adding manifests
  adding file changes
  added 1 changesets with 1 changes to 1 files (+1 heads)
  3 new obsolescence markers
  obsoleted 3 changesets

  $ cd ../..